JP3903951B2 - Electric hot water storage container - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric hot water storage container used as an electric pot for home use, and more specifically, a bottom wall of a metal container for storing the content liquid is formed with an upward convexity and a downward opening. The present invention relates to an electric hot water storage container that is heated and stored by using a heater applied to the lower surface of a ceiling wall of a recess to heat the content liquid contained in the container to boil or keep warm.
[0002]
[Prior art]
Such electric hot water storage containers are well known in the art (for example, see Patent Documents 1 to 3) and are widely used. The heaters described in any of Patent Documents 1 to 3 are mounted in substantially the same manner. Referring to FIG. 1, which shows an embodiment of the present invention in a common range, the bottom wall 2 of the container 1 that contains the content liquid is formed with a concave portion 3 that has an upward convexity and is opened downward. The heater 4 is held by being applied to the lower surface of the ceiling wall 3 a of the recess 3. Although the heater 4 is described in Patent Document 1, as shown schematically in FIG. 6, a hot water heater wire 4a made of a thick nichrome wire or a heat insulating heater wire 4b made of a thin tape-like nichrome wire is replaced with a donut-shaped core plate. 4c or the like is alternately wound by using the positioning portions 4d, and the disk is sandwiched between mica to be stored in a metal case. One heater wire is used regardless of whether it is heated or kept warm, and it is commonly used for boiling and keeping warm by energization control such as changing the heat generation capacity according to the duty ratio.
[0003]
As shown in FIG. 1, such a heater 4 is connected to a metal heat shield plate 6 that is attached to the outer peripheral portion of the bottom wall 2 of the container 1 via a mounting bracket 5. A spring plate 107 sandwiched with a member or the like is pressed against the ceiling wall 3a of the recess 3 and held. On the other hand, the case of the heater 4 is fixed to the ceiling wall 3a by spot welding.
[0004]
The container 1 described in Patent Document 1 is a single aluminum container, and the containers 1 described in Patent Documents 2 and 3 are vacuum double containers as in the embodiment of the present invention shown in FIG. . In addition, the vacuum double container described in Patent Document 2 is described in Patent Document 3 in that the heater 4 is applied to the single bottom part attached to the bottom part through a seal packing. The vacuum double container according to the embodiment of the present invention is different from the case where the heater 4 is applied to the single bottom formed integrally therewith.
[0005]
In any case, in order to heat the content liquid in the container 1 with such a heater 4 with high thermal efficiency, it is important to increase the degree of adhesion of the heater 4 to the container 1. Therefore, the ceiling wall 3a was initially made flat. However, the ceiling wall 3 a was deformed by thermal expansion due to the heating of the heater 4, and the ceiling wall 3 a was not in close contact with the heater 4. In order to prevent this, conventionally, as shown in FIG. 5, the ceiling wall 3a has a curved shape that protrudes downward, and the heater 4 is pressed against the ceiling wall 3a to cause elastic push-back deformation of the ceiling wall 3a. It is also done to increase the degree. As an example, the curved shape is a spherical surface having a curvature radius R of about 3000 mm having a center of curvature P on the axis 41 of the container 1 and about 260 times the opening diameter of the concave portion with respect to the ceiling wall 3a of the concave portion 3 having an opening diameter of about 122.6 mm. A temperature sensor 8 as shown in FIG. 1 for detecting the temperature of the content liquid is provided on the lower surface of the central portion with an upward protruding portion 3e having a diameter approximately the same as the inner diameter of the donut-shaped heater 4 and about 33 mm. It is the part to apply.
[0006]
[Patent Document 1]
Japanese Utility Model Publication No. 03-095821 (FIGS. 1 and 2)
[0007]
[Patent Document 2]
JP-A-10-179394 (FIGS. 2 and 3)
[0008]
[Patent Document 3]
JP 2000-93307 A (FIGS. 1 and 4)
[0009]
[Problems to be solved by the invention]
However, while the present inventors repeatedly performed a durability test over time, a decrease in heating efficiency, a deterioration in the deformation of the heater, and uneven heating were observed, and sometimes the fusing of the heater was observed. In connection with this, when the present inventor conducted various experiments and studied repeatedly, the heater fusing is often seen in the tape-shaped heat retaining heater wire 4b. In many cases, the heat-insulating heater wire 4b that has been melted is caused by a short circuit in contact with the adjacent water heater wire 4a or the like that is curved on the outer peripheral side of the heater 4 as shown by a virtual line 4e in FIG. Was recognized. In addition, even when the adjacent heater 4a was not in contact with or melted, there was a relatively large deterioration in the temperature of the heat retaining heater wire 4b and uneven heating. It is considered that the heat retaining heater wire 4b is curved in such a manner that a part of the heater 4 that is partially lifted is bent during thermal expansion.
[0010]
Regarding such a float, when the present inventors repeated further experiments using pressure-sensitive paper and repeatedly studied, the float is often generated in the outer peripheral portion that can be said to have been affected by the curved shape of the ceiling wall 3a. This is a place where the heat retaining heater wire 4b is bent or melted. Further, the contact state may not be constant even in the circumferential direction due to distortion of the ceiling wall 3a. Furthermore, the ceiling wall 3a is inverted to an upwardly curved shape and the heater 4 is hardly in contact.
[0011]
The distortion of the ceiling wall 3a, which disperses the contact in the circumferential direction, is deep drawing to form the joint fitting welded part of the single container or vacuum double container, and the inner and outer cylinders constituting the vacuum double container. In order to avoid this, it seems to be caused by dimensional deviation or thermal deformation caused by welding heat, such as a welded part that joins the bottom part and the body part of the container, or a welded part between the bottom part of the inner cylinder and the outer cylinder. It is.
[0012]
The inversion of the curved shape of the ceiling wall 3a is the curvature of the ceiling wall 3a. radius Is as large as about 3000 mm as described above, and the curved shape is a spherical shape and the heater 4 is a container on the spherical surface of the ceiling wall 3a even though it is almost flat as seen in FIG. The bending rigidity between the bending start point 3c and the outer peripheral end 3d where the ceiling wall 3a is connected to the peripheral wall 3b when pressed against the bending start point 3c that makes contact with the inclined plane with respect to the plane perpendicular to the axis is high and is familiar to the heater 4 It seems that this is because the force that lifts the outer peripheral end 3d side works more strongly than the deformation that makes contact, resulting in reversal similar to a reversal spring.
[0013]
An object of the present invention is to provide an electric hot water storage container having good heating efficiency and durability in which adhesion between a heater and a container bottom can be suitably achieved based on the above new knowledge.
[0014]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the electric hot water storage container of the present invention forms a concave portion that has an upward convexity and opens downward on the bottom wall of a metal container that contains the content liquid, and the ceiling wall of the concave portion. On the bottom Pressed and held In the electric hot water storage container that is heated and heated and heated and stored for use by heating the content liquid stored in the container, a downwardly convex curved shape to be given to the ceiling wall of the container is formed on the axis of the container. Central part almost tangent to a perpendicular plane Left Around Curve that is almost tangential to a plane perpendicular to the container axis From the starting point to the periphery The heater is deformed to fit the heater by pressing it. Was it Special It is a sign.
[0015]
In such a configuration, the convex curved shape under the ceiling wall of the recess formed in the bottom wall of the container has a starting point that is substantially tangent to a plane perpendicular to the axis of the container around the central portion. Therefore, the heater is pressed against the bending start point substantially in the tangential direction. Therefore, the conventional spherical surface does not show strong tension rigidity as in the case of contacting with the heater with a clear inclination angle, and is easily deformed so as to be compatible with the heater that is pressed and exerts flexibility. Reduces the force to lift the outer peripheral edge by an amount that is easy to adjust, and reduces the distance to the outer peripheral edge and increases the rate of curve change by the amount that the bending start point that is almost tangential to the plane perpendicular to the axis of the container is off the center. Since the resistance against lifting on the outer peripheral end side is increased, the contact area to the ceiling wall of the heater is also sufficient on the outer peripheral side while avoiding reversing the ceiling wall of the recess in the bottom wall of the container To widen the area. In addition, the distance to the outer peripheral edge is small and the rate of change in curvature can be increased by the amount of the origin of the curve that is almost tangent to the plane perpendicular to the axis of the container on the ceiling wall. The resistance against dimensional change and distortion is also increased, and the adhesiveness with the heater can be increased by the amount easily maintaining the predetermined shape. These improve the heating efficiency. In addition, it is possible to improve the durability by avoiding problems such as deformation deterioration due to floating of the heater wire, uneven heating, and fusing due to contact with the adjacent heater wire.
[0029]
Further objects and features of the present invention will become apparent from the following detailed description. Each feature of the present invention can be employed alone or in combination in various combinations as much as possible.
[0030]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, in order to understand the present invention. In addition, the following description and illustration show the specific example of this invention, Comprising: Description content of a claim is not limited.
[0031]
The electric hot water storage container of the present embodiment is an example of a household electric pot, and as shown in FIG. 4, the bottom wall 2 of the metal container 1 that stores the content liquid has an upward projection and faces downward. The recessed portion 3 that is opened is formed, and the content liquid stored in the container 1 is heated by the heater 4 applied to the lower surface of the ceiling wall 3a of the recessed portion 3 so as to boil or keep warm, to store the hot water for use. The content liquid is led out through the lead-out path 7 connected to the ceiling wall 3a of the concave portion 3 for use. As the heater 4, the above-described one schematically shown in FIG. 6 is adopted as an example. As shown in the figure, the lead-out path 7 may be one in which the content liquid is drawn into a pumping system by a centrifugal pump 8 provided in the middle and used for use, or may be pushed out by a pressurizing manual pump or an electric pump. An electric pump and a manual pump may be used in combination, or a system in which the container 9 having or holding the container 1 is tilted and led out may be employed alone or in combination.
[0032]
As shown in FIG. 1 and FIG. 4, the container body 9 covers the heater 4 and the centrifugal pump 8 which are applied to the bottom wall 2 which is a single bottom of the container 1 from the outside at least to protect them and to protect others. It is preferable to prevent the influence of heat and adjust the appearance. However, it is not necessary to cover the other parts. In the example shown in the drawing, the exterior case 11 including the lead-out path 7 is covered with a synthetic resin exterior case 11 in which a body portion and a bottom portion are integrally formed. As shown in FIG. 4, the outer case 11 is fitted and joined to a shoulder portion 12 made of a synthetic resin to constitute a container 9 containing the container 1, the heater 4, the lead-out path 7, and the centrifugal pump 8. A hollow lid 13 made of synthetic resin is provided in an opening formed in the shoulder 12 at the upper end of the vessel body 9 and is supported by a hinge pin 14 at the rear of the shoulder 12 so that it can be opened and closed.
[0033]
In the specific example shown in FIG. 4, a lock member 15 that locks the lid 13 in a closed state by elastically engaging the engaging portion 12 a on the shoulder 12 side when the lid 13 is closed at the front portion of the lid 13. Is provided by being biased by a spring 16 in the engaging direction, and a lock release member 17 is provided for releasing the lock by removing the lock member 15 from the locking portion 12a by retreating the lock member 15 against the spring 16. The unlocking member 17 is a lever member that rotates in an arc around the shaft 18. When the front end 17 a is pushed in, the lock member 15 starts to retract, and the rear end 17 b that rises at that time is hooked on the finger and pulled up. The lid 13 can be lifted and opened following the unlocking of the lock member 15.
[0034]
As shown in FIG. 4, the lead-out path 7 extends to the front portion of the shoulder portion 12 and protrudes into a protruding portion 12 b protruding like a bowl, and is provided with a water stop valve 21 at the time of falling, a water stop valve 22 at the time of forward tilt, and the like. The previous discharge port 7a opens downward from the lower surface of the projecting portion 12b so that the derived content liquid flows out for use. An operation unit 23 is provided on the upper surface of the projecting portion 12b. Operation keys for selecting various operation modes and heat insulation temperatures, a display unit for indicating a setting state and an operation state, and the like are provided. A control board 28 equipped with a switch 24, a liquid crystal display unit 25, a display lamp 26, or a control unit 27 such as a microcomputer for controlling the overall operation is provided to respond to the operations, and various power sources are created. A power source / drive system substrate 29 that drives the heater 4 and the centrifugal pump 8 in accordance with the control from the control unit 27 is disposed between the container 1 and the bottom of the outer case 11 together with the centrifugal pump 8. The power source / drive system substrate 29 is accommodated in a circuit box 31 that is integrally molded or attached to the bottom of the outer case 11 so that it can be protected from water leakage and intrusion water from the lower part. The circuit box 31 has a two-member structure that is opened and closed up and down.
[0035]
A projection 3e that protrudes upward as shown in FIGS. 1 and 4 is further formed at the center of the ceiling wall 3a of the recess 3 and a temperature sensor 32 that detects the content liquid temperature is applied to the inside of the projection 3e. The obtained temperature information is used for control of the control unit 27. Here, the temperature sensor 32 is active in a state in which the content liquid is left in the lowest space 33 around the ceiling wall 3a at the moment when the amount of the content liquid falls below the ceiling wall 3a. It is designed to be a vacant sky. As a result, before the content liquid remaining in the airing prevention state disappears, the abnormal temperature rise due to the active airing state in the protruding portion 3e can be immediately detected and determined. Therefore, there is no other thermal adverse effect by creating this positive emptying state.
[0036]
A bottom cover 34 made of synthetic resin as shown in FIGS. 1 and 4 can be attached to and detached from the opening 11a at the bottom of the outer case 11 by using a plurality of claws (not shown) provided on the outer periphery and one screw. A rotating seat 35 is rotatably mounted on the outer periphery of the bottom lid 34. When the device body 9 is placed, it is grounded by the rotating seat body 35, and the device body 9 rotates on the rotating seat body 35. I can move and change the direction.
[0037]
In the present embodiment, in particular, a concave portion 3 is formed in the bottom wall 2 of the metal container 1 containing the content liquid as shown in FIGS. FIG. 1 and FIG. 4 show an electric pot in which a liquid 4 contained in a container 1 is heated by a heater 4 applied to the lower surface of the ceiling wall 3a of the No. 3 to be heated and heated and stored for use. The downwardly convex curved shape given to the ceiling wall 3a of the container 1 is surrounded by the origin 3c around the central portion 3a1 that is substantially tangent to the plane A perpendicular to the axis 41 of the container 1 as shown in FIGS. It is forming towards. The curved shape may be a smooth curved surface in which the height of the ceiling wall 3a gradually increases from the starting point 3c toward the outer periphery, may include an elliptical curved surface, and may be a set of curved surfaces having a plurality of curvature centers.
[0038]
Thus, the convex curved shape below the ceiling wall 3a of the recess 3 formed in the bottom wall 2 of the container 1 is substantially tangential to the plane A perpendicular to the axis 41 of the container 1 around the center 3a1. Therefore, the heater 4 is pressed against the curved starting point 3c substantially tangential to the plane A. Therefore, the conventional spherical surface does not show strong tension rigidity as in the case of abutting the heater 4 with a clear inclination angle, and is easily deformed so as to be compatible with the heater 4 that exerts flexibility and is pressed. Further, the force that lifts the outer peripheral end side by an amount that is easy to adapt to the heater 4 is reduced, and the distance Y from the center O to the outer peripheral end 3d is the distance Y from the center O to the curvature starting point 3c that is substantially tangential to the plane A. Since the curve change rate can be made small and high, the resistance against lifting on the outer peripheral end 3d side is increased. Therefore, the contact area of the heater 4 to the ceiling wall 3a extends to the outer peripheral side and widens while avoiding the inversion of the ceiling wall 3a of the recess 3 in the bottom wall 2 of the container 1. . Further, as shown in FIG. 2, the distance Y to the outer peripheral end 3d is small and the curve change rate can be increased by the amount of the curvature starting point 3c, which is substantially tangential to the plane A of the ceiling wall 3a, away from the center O by the distance X. The resistance against dimensional change and distortion due to the heat effect from the surrounding welded portion 43 is also increased, and the adhesion to the heater 4 can be increased by the amount easily maintaining the predetermined shape. These improve the heating efficiency. In addition, it is possible to improve the durability by avoiding problems such as deformation deterioration due to floating of the heater wire, uneven heating, and fusing due to contact with the adjacent heater wire.
[0039]
Moreover, in the specific example shown in FIGS. 1-3, in addition to the above, the downward convex curve shape given to the ceiling wall 3a of the container 1 is further changed to the curvature of the peripheral portion 3a2. radius Is small, the curvature inside this periphery radius Is formed to be large. If it does in this way, the curved shape convex under the ceiling wall 3a of the recessed part 3 formed in the bottom wall 2 of the container 1 will be the curvature of peripheral part 3a2. radius Is small and the curvature of the inner side 3a3 of the peripheral portion 3a2 radius Because of the large curvature, the large curvature at the inner side 3a3 of the ceiling wall 3a radius The inner surface 3a3, which is a curved surface of the container, is a spherical surface having a center of curvature on the axis 41 of the container 1 as in the prior art. radius Even if an attempt is made to lift the outer peripheral end 3d side by abutting with a clear inclination angle when pressing the heater 4 and exhibiting a strong tension rigidity, the peripheral portion of the inner peripheral end of the outer peripheral end 3d 3a2 has a small curvature radius By forming a steep falling portion as shown in FIG. 2 and FIG. 3 continuing to the inner side 3a3, a high resistance against the lifting force is exerted to strongly prevent the ceiling wall 3a from being inverted. Accordingly, the curvature of the heater 4 with the deformation of the ceiling wall 3a is avoided while avoiding the inversion of the ceiling wall 3a of the recess 3 in the bottom wall 2 of the container 1. radius To the inner peripheral part of the peripheral part 3a2 which is a small curved part. Also curvature radius The curved shape formed by the peripheral portion 3a2 which is a small curved portion and the corner portion 3f between the peripheral wall 3b of the concave portion 3 has a high deformation rigidity in the folded shape portion 3g where the bending direction is reversed in the middle, and the welded portion around the outer periphery Even if there is 43 and the welding heat reaches, it is difficult to be subjected to dimensional change and distortion, and the curvature is to make contact with the heater 4 on the inner side 3a3. radius It is possible to prevent the large curved portion from being distorted and to partially float between the heater 4 and the ceiling wall 3a.
[0040]
Accordingly, the heating efficiency is further improved, and the durability can be further improved by further avoiding problems such as deformation deterioration due to floating of the heater wire, uneven heating, and fusing due to contact with the adjacent heater wire. As described above, the curved starting point 3c around the central portion 3a1 is not oriented so as to be substantially tangential to the plane A, and an excellent effect can be obtained even if the curved shape has a center of curvature on the axis 41 as in the past. be able to. In addition, as shown in the illustrated example, the inner side 3a3, which forms a large area of the ceiling wall 3a and is in contact with the heater 4, has the bending start point 3c around the central portion 3a1 substantially tangential to the plane A as described above. By being in a shape that comes into contact with the heater 4 in a direction to be a direction, it is more difficult to reverse and more easily contact with the heater 4.
[0041]
For this purpose, as shown in FIGS. 1 to 3, the downwardly convex curved shape to be given to the ceiling wall 3 a of the container 1 is changed to the curvature of the peripheral portion 3 a 2. radius Is small and the curvature of the inner side 3a3 of the peripheral portion 3a2 radius And the curvature of the inner side 3a3 can be satisfied by forming from the starting point 3c around the central portion 3a1 that is substantially tangent to the plane A perpendicular to the axis 41 of the container 1 toward the periphery.
[0042]
As a result, a curved shape protruding below the ceiling wall 3a of the recess 3 formed in the bottom wall 2 of the container 1 is substantially tangential to a plane A perpendicular to the axis 41 of the container 1 around the center 3a1. Therefore, the heater 4 is pressed against the curved starting point 3c oriented substantially in the tangential direction. Therefore, the outer peripheral end 3d side is not deformed so as to be compatible with the heater 4 which exhibits strong flexibility and does not exhibit strong tension rigidity as in the case of the conventional spherical surface, and is easily compatible with the heater 4. The lifting force is reduced, and the distance Y to the outer peripheral end 3d is small and the curve change rate is high by the amount of the curvature starting point 3c that is substantially tangent to the plane A perpendicular to the axis 41 of the container 1 away from the center O by the distance X. As a result, resistance to lifting on the outer peripheral end 3d side is increased.
[0043]
In addition to this, a curved shape protruding below the ceiling wall 3a of the recess 3 formed in the bottom wall 2 of the container 1 is the curvature of the peripheral portion 3a2. radius Is the curvature of the inner side 3a3 of the peripheral part 3a2 radius Therefore, when the heater 4 is pressed against the ceiling wall 3a, the peripheral portion 3a2 inside the outer peripheral end 3d portion has a small curvature even if the outer peripheral end 3d portion side is lifted. radius By forming a steep falling portion that follows the inner side 3a3, a high resistance against the lifting force is exerted to strongly prevent the ceiling wall 3a from being inverted.
[0044]
By these, while avoiding that the ceiling wall 3a of the recessed part 3 in the bottom wall 2 of the container 1 is reversed, the contact area of the heater 4 with the ceiling wall 3a has a curvature. radius It is made to contact in the wide area even to the inner peripheral position of the peripheral part 3a2 which is a small curved part.
[0045]
In addition, the distance Y to the outer peripheral end 3d is small and the rate of change in curvature can be increased by the amount of the curvature starting point 3c, which is substantially tangent to the plane A perpendicular to the axis 41 of the container 1, away from the center O by the distance X. The resistance against dimensional change and distortion due to welding heat from the portion 43 is also increased, and the adhesion to the heater 4 can be increased by the amount that the predetermined shape can be easily maintained. In addition, curvature radius The curved portion 3g formed by the corner portion 3f between the peripheral portion 3a2 which is a small curved portion and the peripheral wall 3b of the concave portion 3 has a high deformation rigidity in the folded shape portion 3g where the bending direction is reversed in the middle, and a welded portion 43 around the outer periphery thereof. Even if welding heat is applied, it is difficult to be subjected to dimensional change or distortion, and the curvature to be brought into contact with the heater 4 on the inner side 3a3 radius It is possible to prevent the large curved portion from being distorted and to partially float between the heater 4 and the ceiling wall 3a.
[0046]
As described above, the efficiency and uniformity of heating can be improved, and problems such as deformation deterioration due to floating of the heater wire, uneven heating, and fusing due to contact with the adjacent heater wire can be avoided to further improve durability.
[0047]
Here, the bending start point 3 c is a circle coaxial with the container 1. Thereby, the contact | adherence effect | action with the heater 4 by the curved shape from the curvature starting point 3c to the peripheral part 3a2 is evenly performed around the axis line 41 of the container 1, and it avoids that the variation in the adhesion degree occurs in the circumferential direction. be able to. Further, the circle at the bending start point 3 c has substantially the same diameter as the inner periphery of the donut-shaped heater 4. Having such a bending start point 3 c is preferable because the adhesion characteristics due to the improved curved shape work without excess or deficiency over the entire area of the donut-shaped heater 4.
[0048]
Furthermore, curvature radius The peripheral portion 3a2 that is a small curved portion is the vicinity of the corner portion 3f of the ceiling wall 3a and the peripheral wall 3b of the recess 3. This makes the curvature radius The peripheral portion 3a2 which is a small curved portion is provided in a very narrow range in the vicinity of the corner portion 3f of the ceiling wall 3a and the peripheral wall 3b of the concave portion 3, and the folded shape in which the bending direction formed by them is reversed in the middle The degree of curvature at the portion 3g increases and the deformation rigidity increases. Therefore, the curvature that the inside 3a3 makes radius It becomes easier to prevent the distortion of the large curved portion, and the contact property with the heater 4 can be further improved, and the peripheral portion 3a2 has a curvature. radius Since the region where the ceiling wall 3a does not follow the heater 4 can be narrowed because of the small curved portion, the heating efficiency is further improved.
[0049]
The corner 3f has a curvature radius With a small peripheral part 3a2 radius An upward ridge as shown in FIGS. 2 and 3 is formed on the large inner side 3a3. As a result, the corner portion 3f has a curvature. radius The peripheral edge 3a2 is provided with a more abrupt falling shape to further improve the deformation rigidity and the resistance to the pushing-up force. Curving curvature radius The adhesion with the heater 4 accompanied by the deformation of the large curved portion can be further enhanced.
[0050]
The container 1 is a metal vacuum double container, and the bottom wall 2 is a single bottom part of the vacuum double container. Thus, since the container 1 is a metal vacuum double container, it becomes a metal container with high heat retention efficiency, and the bottom wall 2 to which the heater 4 is applied is a single bottom part, so that the heating efficiency is double vacuum. Even if there is a thermal effect from many welds 43 around the single bottom as shown in FIG. 2 due to being a vacuum double container, the ceiling wall 3a in the recess 3 is not lowered. It is easy to make the heater 4 in close contact with each other and has high heating efficiency and no uneven heating. The vacuum double container forming the container 1 has a high heat insulation efficiency because the space between the inside and outside 1a, 1b is a vacuum space 1c. However, the heat insulation efficiency is further increased by making the metal material forming the stainless steel with low thermal conductivity. Will be expensive.
[0051]
In the specific examples shown in FIGS. 1 to 3, both the peripheral portion 3a2 and the inner side 3a3 thereof are curved surfaces having a circular arc section having one curvature center P1, P2, and the curvature center P1 of the inner side 3a3 is curved. Although it is slightly closer to the center O side than the starting point 3c, the contact with the heater 4 is inclined by that amount, but it satisfies the relationship that is almost horizontal, that is, substantially tangential to the plane A. is doing. Accordingly, the contact allowance S shown in FIG. 3 accompanied with the deformation with the heater 4 by reducing the radius of curvature R1 by an amount corresponding to the decrease in the distance Y from the portion substantially tangential to the plane A to the outer peripheral end 3d is about the same as the conventional one. In the specific example, the radius of curvature R1 is set to about 1500 mm. Further, the radius of curvature R2 of the peripheral portion 3a2 is set to about 5.5 mm. Further, the radius of curvature R3 of the corner portion 3f is set to about 1 mm. As a result, according to experiments by the present inventors, favorable results were obtained in terms of heating efficiency, uniform heating, and durability of the heater 4.
[0052]
Here, the curvature of the inner side 3a3 which is the facing portion, contact, and close contact portion with the heater 4 radius Curvature of R2 and its peripheral part 3a2 radius It differs from R2 by one digit or more, and the curvature center O1 of the inner side 3a3 that is the facing portion, contact, and close contact portion with the heater 4 is located on the facing region with the annular heater 4. The curvature radius R1 is effective as about 1200 to 2000 mm, and the curvature radius R2 is effective as about 2 to 30 mm.
[0053]
【The invention's effect】
According to the electric hot water storage container of one aspect of the present invention, the curved shape protruding below the ceiling wall of the recess formed in the bottom wall of the container is a plane perpendicular to the axis of the container around the central portion. Since it has a starting point that is substantially tangent and is formed toward the periphery, the heater is pressed against the bending starting point that is substantially in the tangential direction. Therefore, the conventional spherical surface does not show strong tension rigidity as in the case of contacting with the heater with a clear inclination angle, and is easily deformed so as to be compatible with the heater that is pressed and exerts flexibility. Reduces the force to lift the outer peripheral edge by an amount that is easy to adjust, and reduces the distance to the outer peripheral edge and increases the rate of curve change by the amount that the bending start point that is almost tangential to the plane perpendicular to the axis of the container is off the center. Since the resistance against lifting on the outer peripheral end side is increased, the contact area to the ceiling wall of the heater is also sufficient on the outer peripheral side while avoiding reversing the ceiling wall of the recess in the bottom wall of the container To widen the area. In addition, the distance to the outer peripheral edge is small and the rate of change in curvature can be increased by the amount of the origin of the curve that is almost tangent to the plane perpendicular to the axis of the container on the ceiling wall. The resistance against dimensional change and distortion is also increased, and the adhesiveness with the heater can be increased by the amount easily maintaining the predetermined shape. These improve the heating efficiency. In addition, it is possible to improve the durability by avoiding problems such as deformation deterioration due to floating of the heater wire, uneven heating, and fusing due to contact with the adjacent heater wire.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of an electric kettle according to an embodiment of an electric hot water storage container of the present invention.
2 is a cross-sectional view of a bottom wall of a container to which a heater of the electric pot shown in FIG. 1 is applied.
3 is an enlarged cross-sectional view of a half portion of the bottom wall of the container shown in FIG.
4 is a cross-sectional view showing an overall configuration of the electric pot shown in FIG. 1. FIG.
FIG. 5 is a cross-sectional view of a bottom wall of a container to which a heater of a conventional electric pot is applied.
FIG. 6 is a partial plan view showing the internal structure of the heater.
[Explanation of symbols]
1 container
2 Bottom wall
3 recess
3a Ceiling wall
3a1 center
3a2 peripheral part
3a3 inside
3b wall
3c Starting point of curvature
3d outer edge
3f Corner
3g folded part
4 Heater
7 Derivative path
8 Centrifugal pump
9 body
11 Exterior case
12 shoulder
13 Lid

Claims (1)

The bottom wall of the metal container that contains the content liquid is formed with a concave part that opens upward and opens downward, and the liquid contained in the container is heated by a heater that is pressed against the bottom surface of the ceiling wall of the concave part. In an electric hot water storage container that is used for boiling water or keeping warm and storing it for use,
A downwardly convex curved shape to be given to the ceiling wall of the container, from a curved origin that is substantially tangential to a plane perpendicular to the axis of the container around a central portion that is substantially tangent to the plane perpendicular to the axis of the container An electric hot water storage container formed toward the periphery and deformed so as to be adapted to the heater by pressing the heater .

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